Heat pump and power production utilizing hydrated salts

ABSTRACT

A thermodynamic cycle for heat upgrading and power production, combining absorption, adsorption and desorption processes, promises high efficiency for heat pump applications and low temperature renewable energy production. The adsorbent regeneration has been replaced from dissolution and separation of electrolyte crystals from a solution electrolytes, saving the regeneration heat consumption.

1. PCT/GR2013/000012 STYLIARAS Vasileios

2. PCT/GR2016/000038 STYLIARAS Vasileios

3. Wikipedia, absorption heat pump

4. International critical tables, solubility of electrolytes.

5. U.S. Pat. No. 3,478,530 Nov. 18, 1969 D.ARONSON

6. U.S. Pat. No. 4,365,475 Dec. 28, 1982

7. Energy Procedia 30 (2012) 294-304

This invention refers to a method and the apparatus for thermal compression of a liquid solution and its application for heat transfer based on absorption and adsorption heat pumps and power production from medium temperature heat sources.

The most common way of heat transfer from lower to higher temperature, otherwise the way for heat upgrading, is based on the vapor compression cycle. When compression is performed trough a mechanical compressor, the cycle is call mechanical compression cooling cycle. Instead, a liquid solution may absorb (condense) the vapor at low temperature and vaporized absorbing heat at higher temperature. Now heat is consumed for compression and the cycle is called thermal compression or absorption cycle. Its (cooling) coefficient of performance (COP) is almost n=0.7. The solution has the same concentration in the evaporator as in the absorber. The pressure ratio between these two equipments depends on their temperature difference.

There is another application suggested (Ref 1), where a saturated solution is cooled from an absorber where it is at high temperature, to lower temperature. This may be an electrolyte solution. The solubility and consequently the concentration decreases. Another phase, like crystals of electrolyte, is created and separated from the solution. The resulting lower concentration solution is vaporized and the vapor is compressed and driven to absorber, in which the remaining solution is also driven. Alternatively, the lower concentration solution is compressed and heated up to the absorber temperature. It is partially vaporized and the vapor performs a cooling or power cycle and then is absorbed in the absorber. The remaining liquid solution returns to the absorber to where the separated electrolyte is driven to, to form the initial solution. Absorption heat is recovered by evaporation.

Another invention (Ref 2) combines two different solutions having the same solvent. The second solution activity does not depend straight on the first solution and may now be much lower than that of the first one, leading to temperature lift. Vapor is produced by the first solution evaporation at low temperature and absorbed by an absorber of the second solution. The second solution is next compressed and heated up to the first solution absorber temperature. It is vaporized there and the vapor returns to the first solution while the rest of the solution returns to the second solution absorber. Cooling, and heating is performed by the solution evaporation and vapor absorption. There is no need for additional evaporators and condensers A few evaporators at different temperature are used for the first solution and each evaporator is combined with an absorber of the second solution so that the rejected heat from the one absorber is recovered by an evaporator, forming absorber—evaporator pairs. If the absorption takes place at the same with the evaporation pressure, temperature lift is achieved, while if the absorption takes place at the same temperature, expansion ration is created that is utilized for power production through a vapor expansion machine like a turbine. A solution of higher and lower (gas) polar substances may be utilized.

The vapor pressure of a solution depends not only on the temperature but of the nature of the solute and the concentration as well. The vapor pressure of the low (electrolyte) concentration solution is higher than that of the high concentration at the same temperature. Pressure gradient is established between the two solutions although they are at the same temperature. In the same way, two solutions may vaporize at the same pressure but different temperature. The vapor pressure of a solution is P=aP°=γmP°, where: P° is the pressure of pure solvent, a is the activity, y is the activity coefficient which is a function of the nature of the solvent and solute and the solution concentration as well. m is the molar concentration.

Another type of heat pump is the adsorption heat pump in which vapor (gas) is adsorbed by an adsorbent. Operation at high temperature may be achieved but the efficiency is also lower than unit. There is a pressure temperature relation, similar to that of pure substance vaporization, when vapor is adsorbed by an absorbent. The same electrolyte, has different adsorption pressure-temperature relation for different degree of hydration. For example, (Ref 6): at p=0, 132 atm, CaCl2*8NH3→CaCl2*4NH3 t=0° C., CaCl2*NH3→CaCl2+NH3 t=160° C., ZnCl₂*NH3→ZnCl₂+NH3 t=400° C. For the gas (vapor) to be released, heat is absorbed, the process is called desorption and the equipment desorber. The reaction can move the opposite direction as well, heat is released, the process is called adsorption and the equipment adsorber. The salt (crystal) that remains when gas has been released, is called regenerated material, as it is ready to adsorb vapour again and release heat. There are different types of desorbers. Usually, the adsorbent (the salt which is going to adsorb vapor) is stabilized onto a heat transfer material. Instead, small size crystals may be provided in a chamber. In other cases, as crystallization takes place, a thin film of electrolyte may caver the surface of the heat exchanger. This film may adsorb the vapour and then a hot solution passes through and dissolves the crystals or, it may be heated to release the vapour. In all these cases, the space where the crystals are included, is a closed space (chamber) provided with a crystal input and output, a vapour output and a pressure valve. This chamber is heated and vapour is produced increasing the pressure. When the pressure reaches a determined level, the valve opens suppling vapour. Vacuum pumps and air compressors may be used to help regulate the pressure during crystal input and output. When the heating medium is not in touch with the crystals, a thin heat transfer sheet separates the crystals from this medium (as is the case of using vapour as a heating medium). There are other types of desorbers too (Ref 7). A similar equipment is used as adsorber.

The coefficient of performance (COP) of the absorption and adsorption cycle, is lower than unit. The above stated new cycles, have high COP but the temperature lift is considerably lower than in the present invention, even for multi stage compression. The disadvantage of electrolyte hydration, turns to advantage now. There is no need for extensive crystallization and separation. The present application can achieve more than 100° C. temperature lift applying just one stage compression. Dissolution of just a few moles of electrolyte is enough for the application. The crystals are dissolved into and separated from the solution in cyclic procedure, bypassing the disadvantage of high operation cycles that appear to chemical (adsorption) heat pumps. The adsorbed vapor is dissolved into the solution instead of being desorbed, saving the consumption of the desorption heat and increasing the efficiency. Finally, the present invention achieves higher temperature lifting, higher vapor compression and high efficiency, with simplest and more economic method than all the previous methods.

Multi stage vapor compression, in a way similar to that presented in (Ref.2), is also applied. The hydrated crystals are separated in a few segments, each segment working in different pressure-temperature conditions. Vapor is produced at different pressure levels by the evaporators and disorbers and absorbed or adsorbed at this pressure but higher temperature. The absorption-desorption heat is recovered. Besides, the vapor produced at the highest temperature, can be expanded for power production before being adsorbed. According to the present method, vapor is produced by adsorption and solution vaporization at low temperature and adsorbed at high temperature. Instead of adsorbent regeneration, dissolution and crystal separation applies, avoiding the consumption of heat of adsorption.

The electrolyte crystal that is connected with molecular forces with the solvent is called hereafter hydrated, no matter if the solvent is water or any other solvent. The type of the formed crystal depends on the particular electrolyte and the temperature. Electrolytes which consist of multi charged ions, usually form crystals of high degree of hydration (mainly with water and ammonia). Polar solvents of small molecules, like water and ammonia, form complexes ease. For example, the solubility of pyrosulfite, Na₂S₂O₅, in water is 5M (mole/kg water)at 100° C. and crystallizes as pure crystal. At 10° C. the solubility is 3M and crystallizes as pure crystal again. At the temperature of 0° C. the solubility is 2.5M and the crystal is hydrated with six water molecules (Na₂S₂O₅*6H2O). The solubility of CuSO₄ is 0.9M at 0° C. and is crystallized with 5 moles of H2O, four of which are with strong bond in the form of [Cu(H₂O)₄]²⁺ and the one with weak bond. Its solubility at 50° C. is 2.5* H2O and at 110° C. is 4.8*3 H2O while at 130° C. the solubility is 5*3H2O. The solubility of Na₂SO₄ is 1*10 at 0° C. and 3.4M as pure crystal at 40° C. There are many other examples like Na₂HPO₄ , Na₂CO₃, FeSO₄. Ammonia NH3 forms complexes with salts also. MgCl₂, ZnCl₂, CoCl₂, LiBr are the most common ammoniates. Water, ammonia and methanol are suggested as solvents and electrolytes having low solubility as the above stated, are preferred as common electrolyte. The terms vaporization, gas release and desorption, mean the production of part of the most volatile solvent in vapor or gas phase. In every case of the method, the fluxes of the solution, vapor and crystals which are heated, recover heat from the solutions that are cooled. Hereafter, the used equipment may be referred to, either by the full name or just by their symbol, like absorber (A1), or just (A1).

FIG. 1 shows the equipment of crystal dissolution (Δ1) from where the solution is cooled, the equipment (K1) and (K1.1) where the separated crystals of low and high degree of hydration respectively are stored, the vapor generator (E1), the desorbent (E2), and the two adsorbents (A2).

FIG. 2 shows the combination of two solutions. (Δ2) is the crystal dissolution equipment and (K2) is the crystal storage equipment of the second solution. (Δ1) are two absorbers of the second solution.

In FIG. 3, (E1) is the vapor generators of the solution, (A1) is the absorber for the vapor from (E1). (EA1), (AE1) is the vapor generator and absorber respectively, (H1.1),(H1.2), (H1.3) are heat exchangers which are used for recovery of heat through the solutions, gases and crystals and from the absorber (AE1), (Δ1) and (Δ2) are dissolution equipments.

In the first application of the method, a saturated electrolyte solution is cooled from the dissolution equipment (Δ1). The solubility decreases and another phase like electrolyte crystals are formed, separated from the solution and gathered into a storage tank (K1.1). These crystals are in hydrated form at this temperature and pressure. The solution contains more electrolytes which are soluble in the solvent and cause strong negative deviation from the ideal solution but their concentration is lower than that determined by the solubility, so that they do not separate. The separated electrolyte is called basic electrolyte, to distinguish from other dissolved electrolytes. The remaining solution is heated, expands, enters an absorber (A1) and then is successively compressed and driven to other absorbers (A1). The crystals from (K1.1) are driven to desorbers (E2), heated to release vapor at a determined pressure, and the vapor is driven to absorbers (A1) to be absorbed. The use of a few desorbers (E2) is preferred to supply vapor to each absorb (A1), so that when the vapor from an (E2) is depleted, vapor from the next (E2) is supplied to ensure continuous vapor flow. Besides, more (E2) are used so that vapor can be produced at different pressure levels. Each set of (E2) working at the same pressure, is combined with an absorber (A1). The crystals from (K1.1) are first driven to an (E2) where the physically bonded moisture, is first vaporized. The pressure of the solution, leaving absorbers (A1), is regulated, heated (or cooled, depending on the absorption and dissolution temperature) and driven to the dissolution equipment (Δ1), where the remaining in (E2) crystals of lower hydration degree, are also driven to be dissolved and form the initial solution. The pressure of (E2) is selected according to the available heat source temperature. The vapor that is produced at the highest temperature, may be expanded for power production. The solution may be expanded before crystal separation, depending on the required temperature-pressure conditions. In this case, crystals from (E2) are compressed before enter (Δ1). Solution cooling and crystal separation may take place in more that one stages and the dissolution may be performed in the same stages into the solution that returns to (Δ1) after (A1)

Polar substances of low boiling point and small molecular weight like water, ammonia, alcohols like methanol, e.t.c. are preferred for solvent. Mixtures (solutions) of substances of considerable different boiling point may also be used. In this case the more volatile substance is called gas. Such an example is a water/ammonia solution. In this case, the pressure, the temperature and the basic electrolyte of the solution that is being cooled, is selected so as the formation of crystals hydrated with the more volatile substance are favored. The pressure of (E2) is also regulated so as desorption of this substance is favored. Electrolytes composed of multi charge ions appearing high degree of hydration at low temperature, are suggested. It may be calcium chloride CaCl2, cupper salts, magnesium sulfate MgSO4, e.t.c., depending on the desired temperature lift. Electrolytes of single charge ions that are not hydrated or are a little hydrated, like KCLO4, sodium NaOH and potassium KOH hydroxides, lithium chloride and lithium nitrate LiNO3, are suggested for the case the adsorption is based mainly on the moisture of crystals. A heat exchanger, transfers heat from the being cooled solution to that which is heated after cooling. The temperature of crystal dissolution is that corresponding to their hydration number. Suppose a solution of cupper sulfate is cooled from the temperature in which it crystallizes as (CuSO4*3H2O), to the environmental temperature. The hydrate that is formed, is CuSO4*5H2O. It is separated, absorbs heat from the heat source which is to be upgraded, turns to CuSO4*3H2O and is dissolved in the solution, while the pressure of the solution is regulated, and the solution enters (A1) to absorb the vapor. The solution temperature and pressure is regulated again and enters (Δ1). The absorbed heat for the vaporization of two moles of water (5-3) is almost 20 Kcal (cooling effect), the rejected (heat effect) is the same, while the required heat for crystallization is almost 6 Kcal.

In a second application that is depicted in FIG. 1, the solution is cooled from (Δ1) to the lower temperature in which the basic electrolyte is formed in the lowest hydration degree. preferably as pure crystal. The formed crystals are gathered in a storage tank (K1). The solution is cooled again and crystals of higher hydration degree are gathered in (K1.1). Crystals from (K1) are dried and driven to the adsorbers (A2). The remaining solution after the last separation, is expanded and enters vapor generator (E1) where part of the solvent is vaporized. The vapor is adsorbed by crystals in, one of the adsorbers (A2). Crystals from (K1.1) are driven to (E2) and the produced vapor is driven for adsorption by another (A2). The remaining solution, as well as, the crystals from (A2) and (E2), are driven to (Δ1) to reform the initial solution. It is preferred that crystals from E2 and A2 are dissolved in different dissolution equipment (Δ1), according to their hydration degree. The solution from the one (Δ1), enters the next (Δ1). The fluxes of solution, crystals and vapor that are heated, recover heat from the solution that is cooled. Heating, is the most effective drying way for crystals of (K1). The resulting vapor may either be absorbed by the solution or be condensed. In case of condensation, the crystals from (K1) are driven to a desorber (E2.2), the resulting vapor from the drying process, is heated by a few degrees and compressed so that its condensation temperature becomes higher than that of vaporization from the crystals. Next, the vapor is driven to the heat providing section of the (E2.2) to dry the next amount of crystals. The condensed vapor, which is solvent in liquid phase, is driven to a vapor generator (E1) for vaporization. The solution in (Δ1) may be saturated in a second electrolyte, which electrolyte is now separated during the first cooling stage and is gathered in (K1). These crystals are dried and driven to (A2). The second electrolyte has been selected so as the vapor adsorption temperature is higher than that of the basic electrolyte under the same conditions. The pressure of (E2) has been selected so that only solvent from the basic electrolyte crystals is vaporized. An example is the use of calcium chloride (CaCl2) as basic and the zinc chloride (ZnCl2) as second electrolyte, using ammonia as solvent.

In a third application (FIG. 2), a first solution is combined with a second solution having the same solvent and the same basic electrolyte. Additional soluble electrolytes have been dissolved into the second solution to create strong negative deviation. Only the basic electrolyte has been dissolved in the first solution, which electrolyte is separated and stored into (K1) and (K1.1) under different hydration degree. The basic electrolyte is preferred to be slightly soluble and crystallize as pure crystal in the first stage of cooling. The remaining after the cooling process solution, enters vapor generator (E1), where part of the solvent is vaporized. Crystals from (K1.1) are driven to (E2) where vapor is also produced. The crystals from (K1), are driven to a dissolution equipment of the second solution (Δ2). From there, the second solution is cooled and electrolyte is separated under higher than in (K1) hydration degree and stored in a storage tank (K2). The remaining solution is heated and enters absorbers (A1) and from there enters (Δ2). The vapor from (E1) is absorbed by the one absorber (A1) and the vapor from (E2) by the other (A1). The second solution is compressed to the proper pressure after each absorber. The crystals from (K2) are driven to (Δ1) to be dissolved. The crystals from (E2) are dissolved into (Δ1). The amount of crystals transferred from (K1) to the second solution equals the amount of crystals that is transferred from (K2) to the first solution. The solvent that is transferred as vapor from (E1) and (E2) to the second solution, returns to the first solution through the hydrated crystals of (K2). Highly soluble electrolytes, in water (used as solvent), are: NaOH, KOH, LiOH, ZnCl2, LiBr and combination of those. In case that ammonia is used as solvent, NaSCN, LiSCN, LiNO3 may be used as soluble electrolytes.

Let's see the application using Na₂S₂O₅ as the common electrolyte and 1 kg of water as solvent. The first solution is saturated at temperature 100° C. in (Δ1). From there, it is cooled to 10° C. where the solubility is 3M. Thus, 2 mole of the salt are separated and gathered in (K1) as pure crystals. The solution is cooled again to 0° C. where the solubility is 2.5 M and 0.5 mole of Na₂S₂O₅*6H2O are separated in (K1.1). The remaining solution is vaporized and 12 mole of water vapor are produced and absorbed by the second solution (A1). The second solution starts cooling from (Δ2) where the concentration is 4.5 M, down to 0° C. (2.5 M), rejecting (4.5-2.5) 2 mole of Na₂S₂O₅*6H2O (K2). The desorbent (E2) is not used. The crystals from (K1.1) are dissolved into (Δ1). 2 mole of pure salt from (K1) are dissolved into (Δ2) and 2 moles of Na₂S₂O₅*6H2O from (K2) are dissolved into (Δ1). Finally, 2 moles of salt are transferred from the first to the second solution and vice versa. 12 moles of water are transferred as vapor from the first solution to the second and return to the first solution through the salt (2 mole salt* 6H2O). Soluble electrolytes like KOH, ZnCl2, LiBr are also dissolved into the second solution, so that the water activity in (A1) is much lower than in (E1).

The application works better using as solvent, a volatile substance dissolved into a liquid solvent. The volatile substance is vaporized in (E1), while the liquid solvent does not form hydrates with the salt. Such a mix solvent may be ammonia dissolved into organic polar liquid of long chain molecule like high boiling point amines and PG. The pressure during cooling, is regulated to favor the formation of hydrates of the volatile substance only.

In a fourth application (FIG. 3), the solution from (Δ1), is cooled, expands, enters an absorber (A1), absorbs vapor coming from a vapor generator (E1), is compressed to the pressure of (Δ1), is cooled through an absorber (AE1) absorbing vapor coming from the described below vapor generator (EA1), keeps cooling and rejects the electrolyte which is stored into the storage tank (K1.1). The solution expands and enters vapor generator (E1) where part of the vapor is released and absorbed by (A1) as stated above. After that, the solution is compressed, heated and enters another dissolution equipment (Δ2) in which another electrolyte is dissolved and then the solution enters the vapor generator (EA1) that stated above. Vapor is released there and then the solution is cooled to separate this electrolyte and then the solution is heated and enters (Δ1).

The solvent is a pure polar solvent like water or ammonia as stated before. Vaporizing the solution through (EA1), the amount of solvent in the solution is reduced, consequently the resulting solution entering (A1), has higher electrolyte concentration and lower solvent vapor pressure. The solution entering (AE1), has higher solvent concentration than that exiting (EA1) because of the solvent which absorbed into (A1). To equalize the solvent activity between (EA1) and (AE1), the dissolved in (Δ2) electrolyte is selected to carry and add to the solution which is vaporized, a lot of solvent molecules, meaning that it is a highly hydrated electrolyte. In contrast, the dissolved into (Δ1) electrolyte, is selected not to be hydrated but exhibiting negative deviation. The method is applicable even by dissolving only one of the electrolytes. The method is also applicable in the case that a gas has been dissolved into the solvent and electrolytes that decrease and increase gas solubility are dissolved into (EA1) and (AE1) respectively. The change in solvent solubility can be repeated by applying a second pair of (EA1/AE1), in a way that the solution exiting the first (EA1), enters the second (EA1) and rejecting electrolyte after the first (AE1), enters the second (AE1). The same set up can be repeated and the first apparatus cooperates with the second, in a way that he vapor from the (E1) of the first set up is absorbed by the absorber (A1) of the second set up and the vapor from (E1) of the second set up is absorbed by the absorber (A1) of the first.

An example of one stage-one set up apparatus, application, is the use of the aqueous (pure H₂O solvent) LiBr/ZnBr₂/CaBr₂ (1:2,1:0,3) solution (data from Ref 5). The solution is vaporized in (E1) at temperature t=80F, salt concentration 75% w. At these conditions the resulting pressure is 10 mmHg. The solution is compressed at 500 mmHg, heated to 280 F and enters (EA1). Is vaporized to t=500 F where the salt concentration is 94%. Is cooled, expands to p=10 mmHg and enters (A1) absorbing the vapor from (E1). The absorption temperature is 260 F. Heat of 80 F is transferred to 260 F. Four mole of zinc sulfate (ZnSO4)*7H2O are added in (Δ1) and separated after (EA1). It means that the solution in (EA1) has (4*7) 28 mole (28*18=504 gr) of additional water during vaporization. If 504 gr of water are absorbed through (A1), the concentration will be the same in (EA1) and (AE1) and the vapor is absorbed at the same temperature and pressure, so that absorption heat is fully recovered.

When the method is going to be used for power production, the absorber of the outlet of this machine is connected at the liquid exit of the crystallizer unit (K1)

In a fifth application two solutions are combined. The first one, from the dissolution equipment (Δ1), enters an absorber (A), then starts cooling, electrolyte crystals are separated and driven to (Δ1), while the solution is heated, expands and enters vapor generator (E1), is compressed, heated and enters (Δ1). The second solution from a dissolution equipment (Δ2), enters vapor generator (E), is cooled, the remaining solution is heated, expands and enters absorber (A1) absorbing vapor from (E1), compressed, heated and enters (Δ2), where the separated crystals enter too. Mixed solvent (liquid-gas) is preferred and the dissolved in (Δ2) electrolyte is such that increases the gas pressure (reduces the gas solubility). The dissolved in (Δ1) electrolyte, increases the gas solubility. The method can work applying only dissolution in (Δ2). The two or just one of the electrolytes, are used to equalize the gas pressure of (E) with (A), so that these equipments work at the same pressure and temperature. The gas concentration in the second solution (A1) is lower than in the first (E1).

For the crystals to be formed at the end of the cooling process, heat is absorbed by the crystals from the solution. It means that the remaining solution start heating from lower temperature than the temperature of the solution just before crystal formation. It makes possible complete heat recovery from the solution that is cooled. Otherwise, the solution that is been cooling, is further cooled by the ambient air or another external source, before start heating again. The heat recovery is performed through heat exchangers (H1.1), (H1.2), (H1.3).

To implement the methods, equipments widely used in the industry are utilized. Vapor generators (evaporators), absorbers, heat exchangers, liquid pumps etc, are connected in the array described in each method.

Heat exchangers may also be used for the recovery of absorption heat from the vapor generators. It is preferred though, that vapor generator is included into the absorber. The vaporized solution passes inside of tubes. The produced vapor is separated from the remaining solution and is driven into the absorber shell that surrounds the vapor generator tubes. In the same space is driven the liquid which is going to absorb the vapor. Ionic liquid can be used when electrolyte is not dissolved, or as electrolyte when it crystallizes and separates at low temperature. Gas selectively permeable membrane can used during vaporization. The crystals may be separated by deposition alternatively on the one and the other heat transfer surface and dissolved by the heating solution which flows from the other side. 

1. Method for heat transfer to higher temperature and power production, in which electrolyte solutions are used and such a saturated solution is cooled from high temperature from a dissolution equipment (Δ1), the solubility lowers, another phase like crystals of the electrolyte are formed, separated and stored in a storage tank (K1.1), the resulting solution is vaporized at successively higher pressure through vapor generators (E1), so that vapor of the solvent is produced, the vapor of each vapor generator is absorbed (A1) by a solution of lower solvent activity at the same pressure but higher temperature, which is the temperature of the next vaporization, so that absorption heat is used for vaporization, the vapor generator which works at the higher than the others temperature, is connected with a vapor expansion machine through a flow regulating valve which can direct part of the vapor for expansion and the rest for absorption, this machine is connected with an absorber working at low temperature and connected with the other absorbers, the remaining from the vaporization process solution as well as the separated crystals (K1.1) return to the dissolver (Δ1) to form the initial solution whilst the solution, the vapor and the crystal fluxes that are heated recover heat from the solution which is cooled, which method is characterized by: the initial solution is saturated in an electrolyte which is hereafter called basic electrolyte and is hydrated at the lower temperature of cooling, while other soluble electrolytes are included, in such a concentration that they do not separate from the solution, the vaporization processes are replaced by vapor desorption and the vapor generators (E1) by desorbers(E2) supplied with crystals from (K1.1), they are heated producing vapor, the remaining after the crystal separation solution, is heated, expands and enters the first of the absorbers (A1) and then is successively compressed and driven to other absorbers (A1) where vapor is also driven and absorbed and then the solution enters dissolver (Δ1), where the remaining in desorbers (E2) crystals also enter, forming the initial solution, when the pressure in each desorber (E2) reaches the determined value, the valve opens and supplies vapor to the connected absorber (A1), each absorber (A1) is connected with a few desorbers (E2) operating at the same pressure, so that when the vapor coming from one of them is exhausted, vapor from the next is provided, solution cooling and crystal separation may take place in more than one stages, as the dissolution may also be done, polar substances of low boiling point like water, ammonia, low boiling point amines, alcohols and mixture of those like ammonia in high boiling point substances, can be used as solvents, where in the last case, the desorption pressure is regulated so that the most volatile substance is desorbed, electrolytes consisting of multi charge ions that form high degree hydrates, like calcium(CaCl2) and magnesium(MgCl2) chlorides are preferred, while when vapor is mainly produced by the moisture of the crystal, single ion electrolytes can also be used.
 2. Method as in claim 1, characterized by the fact that: the hydration degree of the basic electrolyte increases as the crystallization temperature decreases, the solution is first cooled at the temperature in which this electrolyte, is formed, separated and stored (K1) with the lowest degree of hydration, preferably as pure electrolyte and from there they are driven to adsorbers (A2), the solution keeps cooling at lower temperature, crystals of higher hydration degree are separated and stored in (K1.1) and from there, they are driven to desorbers (E2) where they are heated for the vapor to be desorbed, remaining in lower hydration, the remaining solution after the last crystal separation, expands and the solution enters at successively higher pressure into vapor generators (E1) where part of the solvent is vaporized and then the solution is compressed, heated and enters (Δ1), the vapor from the desorbers (E2) and vapor generators (E1) is absorbed through adsorbers (A2), each adsorption and consequently each desorption and evaporation process, may take place at different pressure, the crystals from (K1) are dried by heating in a desorber (E2.2) before driven to (A2) and the vaporized moisture is further heated, compressed and returns to the desorber (E2.2) as a heating means to dry next crystals from (K1), while the condensed vapor is driven to an evaporator (E1), no other soluble electrolytes are dissolved in the solution. the solution in (Δ1) may be saturated in a second electrolyte which vapor adsorption temperature is considerably higher that that of the basic electrolyte, while the solution is saturated with the basic electrolyte at lower than (K1) temperature
 3. Method as in claim 1, characterized by the fact that first and second electrolyte solutions are combined, the two solutions have an electrolyte and a solvent in common the first solution consists only from the common electrolyte and solvent, the first solution is cooled in a few steps so that in the first step the separated crystals are of low hydration, preferably pure electrolyte and stored in (K1) and the separated crystals from the last step are stored in (K1.1), the resulting liquid solution is expanded and driven to vapour generators (E1), compressed successively and evaporated there, the second solution includes more electrolytes that are soluble, causing negative deviation from ideal and at a concentration such that they do not separate, the second solution is cooled from a dissolution equipment (Δ2), crystals of the common electrolyte are formed and separated (K2) at the lower applicable temperature so that they are highly hydrated, the pressure of the remaining solution is regulated and the solution is driven to the absorbers (A1) to absorb the vapor coming from (E1), compressed, heated and enters dissolution equipment (Δ2), the low hydration separated crystals from (K1) are driven and dissolved into (Δ2), whilst crystals from (K1.1) as well as those separated from the second solution in (K2) are dissolved into (Δ1), the crystals from (K1.1) may first driven to a desorbent (E2) where vapour is produced and absorbed into an absorber (A1) and then driven to (Δ1), the amount of the hydrated crystals which are dissolved in the first solution (Δ1), is such that the accompanying solvent is equal to the solvent transferred as vapour through (E1) to (A1) and the amount of this transferred electrolyte equals the amount of electrolyte transferred from the first solution (K1) to the second.
 4. Method as in claim 1, characterized by the fact that the solution from the dissolution equipment (Δ1), expands, enters the absorber (A1) and absorbs vapour from (E1), is compressed to the pressure of (Δ1), enters an absorber AE1 where absorbs the vapour coming from a vapour generator (EA1) stated below, keeps cooling .and the dissolved in (Δ1) electrolyte is separated, from there, the remaining solution enters dissolution equipment (Δ2) where another electrolyte is dissolved, next the solution expands, enters vapour generators (E1), next it is heated, compressed and enters vapour generator (EA1) where is vaporized producing the vapour which is absorbed by (AE1), is cooled so that the dissolved in (Δ2) electrolyte is separated, the solution is heated and enters dissolution equipment (Δ1), the solvent is a pure substance and the dissolved in (Δ2) electrolyte is of low solubility and high hydration whilst the dissolved in (Δ1) is the opposite, the method is also applicable when used with a mixed solvent which consists of a gas dissolved in a liquid, in such case, the dissolved in (Δ2) electrolyte is of reducing gas solubility and the dissolved in (Δ1) is of increasing gas solubility, the method can work applying only one electrolyte dissolution and separation process, a second pair of (EA1/AE1) can be introduced in a way that the solution that exits the first (EA1) enters the second (EA1) and exiting the first (AE1) enters second (AE1), a second similar apparatus can cooperate with the first, in a way that vapour from E1 of the first apparatus enter A1 of the second and vapour from E1 of the second enters A1 of the first. the outlet of the expansion machine, when used, is absorbed at the liquid outlet of (K1)
 5. Method as in claim 1, characterized by the combination of two solutions, where, in the first one, the solution from the dissolution equipment (Δ1) is first driven to an absorber (A) and then cooled to separate the electrolyte, which is driven to (Δ1), the absorbers (A1) have been replaced by vapour generators (El) and the produced vapour is absorbed by the second solution, the second solution from its dissolution equipment (Δ2), is first driven to a vapour generator (E) and then cooled to separate the electrolyte, which is driven to (Δ2), the absorbers (A1) absorb the vapour produced by the first solution, the amount of vapour absorbed by (A1), is produced from the vapour generator (E) and absorbed by the first solution through (A), the solvent is preferably a mixed solvent in which a gas is dissolved, and the dissolved in the second solution electrolyte is of reducing gas solubility while in case of pure solvent it is highly hydrated, in contrast to the first solution electrolyte, which may not be used.
 6. Apparatus for heat transfer to higher temperature and power production, consisted of: a dissolution equipment (Δ1), a crystallizer unit which consists of a crystallizer, a crystal separating equipment and a crystal storage tank provided with a liquid inlet, a liquid outlet and a crystal outlet connection, disorbers (E2) provided with a crystal inlet and outlet and a vapor outlet, absorbers (A1), a heat exchanger, a pressure expansion valve, low pressure liquid pumps and the pipe network connecting the equipments in a way that: the outlet of the dissolution equipment (Δ1) is connected with the liquid inlet of the crystallizer unit through a heat exchanger, the crystal outlet of which unit is connected with a crystal conveyor means with the desorber (E2) and the liquid outlet is connected through the pressure expansion valve with an absorber (A1), this absorber is connected with a next absorber (A1) through a liquid pump and the exit of the this absorber is connected with the dissolution equipment (Δ1) through the heat exchanger and a liquid pump, the vapour outlet of each disorber (E2), is connected with the vapour inlet of one of the absorbers (A1) and the crystal outlet is connected with the dissolution equipment (Δ1), the one direction of the heat exchanger is connected with the dissolution equipment (Δ1) outlet and the crystallizer unit input and the other direction with the liquid outlet of the crystallizer unit and the dissolution equipment (Δ1) liquid input, while in this direction there are outputs and inputs before and after each absorber (A1), heat transfer equipments connecting absorbers (A1) with the disorbers (E2).
 7. Apparatus for heat transfer to higher temperature and power production as in claim 6, in which a disorber (E2.2) for crystal drying, which includes a heat transfer surface separating the crystals from the vapor by which they are heated, a crystal inlet and vapor and crystal outlet in the drying space and a vapor inlet and liquid outlet in the heat supplying space, is included, where: there is a first and a second crystallizer unit in which the liquid outlet of the first is connected with the liquid inlet of the second, the absorbers (A1) are replaced by vapor generators (E1), the crystals outlet of the first crystallizer (K1) unit is connected with the crystal inlet of the disorber (E2.2), the crystal outlet of which is connected with adsorber equipments (A2) with crystal convey means and the crystal outlet of these is connected through crystal convey means with (Δ1), the vapor outlet of disorbers (E2) and vapor generators (E1), are connected with the vapor inlet of (A2) so that each of the (E2) and (E1) that works at the same pressure level is connected with the same (A2), the vapor outlet of the drying space of the disorber (E2.2) is connected with a heating means and the vapor outlet of this means is connected with a vapor compressor, the outlet of which is connected with the vapor inlet of the heating space of the oven, heat transfer equipments connecting adsorbers (A2) with disorbents (E2) and evaporators (E1).
 8. Apparatus as in claim 6, characterized by the fact that two such apparatus are combined, in the first of which, the outlet of the dissolution equipment (Δ1), is connected with the liquid inlet of a first crystallizer unit, the liquid outlet of which is connected with the liquid inlet of a second unit, absorbers (A1) have been replaced by vapour generator (E1), in the second apparatus, the disorbers E2 are not used, the crystal outlet of the first crystallizer unit of the first apparatus, is connected with the crystal inlet of the dissolution equipment of the second apparatus, the crystal outlet of the crystallizer unit of the second apparatus, is connected with the crystal inlet of the dissolution equipment of the first apparatus
 9. Apparatus as in claim 6, characterized by the fact that, the outlet of the dissolution equipment (Δ1), is connected with the liquid input of an absorber (A1) through a heat exchanger and a pressure expansion valve, the outlet of this absorber, is connected with the liquid inlet of another absorber (AE1), through a liquid pump and the outlet of this absorber is connected with the crystallizer unit through a heat exchanger (H1.1), the crystal outlet of which is connected with (Δ1), the liquid outlet of the crystallizer unit is connected with a vapor generator (E1) through an expansion valve, the outlet of which is connected with another dissolution equipment (Δ2), through a liquid pump and the heat exchanger (H1.1).the liquid outlet of this is connected with another vapor generator (EA1), the liquid outlet of (EA1) is connected with another crystallizer unit through another heat exchanger, the liquid outlet of this unit is connected with the first dissolution equipment (Δ1) through the same heat exchanger and the crystal outlet with the second dissolution equipment (Δ2), the vapour outlet of (E1) is connected with the vapour inlet of (A1), the vapour outlet of (EA1) is connected with the vapour outlet of (AE1), this apparatus can cooperate with a second one which is the same, in a way that the vapour outlet of the vapour generator (E1) of the first is connected with the vapour inlet of the absorber (A1) of the second and the same with the absorber (A1) of the first with the vapour generator (E) of the second. the absorber at the outlet of the expansion machine is connected at the liquid outlet of (K1)
 10. Apparatus as in claim 6, characterized by the combination of two such apparatus, in the first of which, the outlet of the dissolution equipment (Δ1), is connected with the inlet of an absorber (A), the outlet of which is connected with the crystallizer unit, dissorbers (E2) are not used, the absorbers (A1) has been replaced by vapor generator (E1) and in the second apparatus, the outlet of the dissolution equipment (Δ1), is connected with a vapor generator (E), the output of which is connected with the crystallizer unit of this apparatus, dissorbers (E2) are not used, the vapor outlet of the vapor generators (E1) of the first apparatus is connected with the vapor inlet of the absorbers (A1) of the second and the vapor outlet of the vapor generator of the second is connected with the vapor inlet of the absorber (A) of the first apparatus. 